Illumination system for a photocopying machine

ABSTRACT

A photocopying machine produces a copy of a page of a bound book placed on a stationary window by moving an optical projection system past the window for projecting the images of successive elongated strip portions of the page onto a light sensitive copy material. The portion of the page placed flat against the window is maximized by providing a downwardly extending wall adjacent an edge of the window to minimize the portion of the page adjacent the binding being pulled out of focus by the binding of the book. Movable past the window with the optical projection system is an illumination system for illuminating an elongated strip portion of the page for projection onto the light sensitive copy material. The illumination system has a physical configuration substantially coextensive with the illuminated strip portion being projected onto the copy paper, and one end of the illumination system is substantially coextensive with the edge of the window adjacent the downwardly extending wall. The illumination system includes an elongated elliptical reflector and an in-line lamp located at the longitudinally extending focal point of the elliptical reflector. Transverse reflectors are located at the opposite ends of the elliptical reflector and extend obliquely to the longitudinally extending focal point of the elliptical reflector for covering the non-light radiating terminal portions of the in-line lamp which is supported at the longitudinally extending focal point by suitable electrical contact means.

. United States Patent 1191 11] 3,807,856 [451 Apr. 30, 1974 Rodriguez ILLUMINATION SYSTEM FOR A PHOTOCOPYING MACHINE Related US. Application Data [63] Continuation of Ser. No. 861,275, Sept. 26, 1969,

[75] Inventor:

abandoned.

[52] US. Cl 355/67, 355/8, 355/11, 355/82, 355/25 [51] Int. Cl. G03b 27/54 [58] Field of Search 355/8, 11, 67, 82, 83, 355/84, 104, 110, 25; 240/1 1.4, 41.3, 41.35

[56] References Cited UNITED STATES PATENTS 2,807,190 9/1957 Oldenboom 355/8 3,637,303 l/l972 Komori 355/8 3,219,799 11/1965 Trumbull 355/3 3,451,752 6/1969 Frank 355/8 3,375,752 4/1968 Fairbanks... 240/1 1.4 R X 3,428,397 2/1969 Elmer 355/11 2,546,482 3/1951 Van Der Grinten..... 355/104 3,398,259 8/1968 Tregay 355/3 X Primary Examiner-Monroe l-l. Hayes 57 0 ABSTRACT A photocopying machine produces a copy of a page of a bound book placed on a stationary window by moving an optical projection system past the window for projecting the images of successive elongated strip portions of the page onto a light sensitive copy material. The portion of the page placed flat against the window is maximized by providing a downwardly extending wall adjacent an edge of the window to minimize the portion of the page adjacent the binding being pulled out of focus by the binding of the book.

Movable past the window with the optical projection system is an illumination system for illuminating an elongated strip portion of the page for projection onto the light sensitive copy material. The illumination system has a physical configuration substantially coextensive with the illuminated strip portion being projected onto the copy paper, and one end of the illumination system is substantially coextensive with the edge of the window adjacent the downwardly extending wall. The illumination system includes an elongated elliptical reflector and an in-line lamp located at the longitudinally extending focal point of the elliptical reflector. Transverse reflectors are located at the opposite ends of the elliptical reflector and extend obliquely to the longitudinally extending focal point of the elliptical reflector for covering the non-light radiating terminal portions of the in-line lamp which is supported at the longitudinally extending focal point by suitable electrical contact means.

2 Claims, 7 Drawing Figures PATENTEDAPR 30 I974 SHLU 2 OF 4 YINVENTOR LEE L- RODRIGUEZ hnuuu wu PATENTED APR 30 I974 sum v3. or 4 INVENTOR LEE LQ. RODRIGUEZ ATTORNEYS sgsomss I P'Arimimmo 1914 sum u or 4 INVENTOR LEE L... RODRIGUEZ ATTORNEYS ILLUMINATION SYSTEM FOR A PHOTOCOPYING MACHINE This application is a continuation of US. Pat. Application Ser. No. 861,275, filed Sept. 26, 1969, now abandoned. g

This invention relates to an illumination system, and more particularly to an illumination'system for use in an electrostatic photocopying machine for producing a copy of a document which is maintained in a stationary position during the copying process.

In an electrostatic photocopying'machine, a copy of a document is produced by illuminating thedocument and projecting the image thereof onto a photoconductive surface of a copy material having a uniform electrostatic charge. The face of the document is placed against a window, and the image of the illuminated document is projected by an optical projection system which is focused on both the window, which is located at an object plane, and the photoconductive surface of the copy paper whichis located at an exposure station. As the photoconductive surface is exposed to the projected image of the document, the uniform electrostatic charge is selectively dissipated according to the light and dark portions of the projected image to form a latent electrostatic image of the document. The portions of the projected image corresponding to the lighter areas of the document have a greater light intensity and hence are more effective in dissipating the electrostatic charge on the copypaper than the portions of the image corresponding to the darker areas of the original. Subsequently, the latent image is developed into a visible image by bringing the photoconductive surface into contact with the visible particles which are electrically attracted to the latent electrostatic image.

To produce an accurate copy of the document, it is necessary for the document to be maintained flat against the window so as to be in focus with the optical projection system projecting the image of the document onto the copy paper. Furthermore, the document must be unevenly illuminated in a manner which compensates for the natural fall off of light intensity due to the angle at which light is radiated from the document and irradiated onto the surface of the copy paper as well as any vignetting inherent with the lens used in the optical projection system. The uneven illumination of the document is necessary so that all portions of the document having the same uniform shade of color will be projected onto the photoconductive surface of the copy paper with a uniform light intensity.

If the document to be copied is a page of a bound book, it is often difficult to place all of the printed portion of the page flat against the window, because the binding of the book tends to pull the adjacent portion of the page away from thewindow and out of focus with the optical projection system. This problem is particularly acute in the case of a large book with narrow margins, for example, a large dictionary. To facilitate the copying of a page of a book, it is desirable to provide a downwardly extending wall adjacent an edge of the window to maximize the portion of the page placed on the window for copying. Such an arrangement facilitate's placing the page to be copied on the window by enabling the adjacent page and portion of the book not being copied to extend beneath the plane of the window with the binding being pressed towards the edge of the window.

When the copy of the document is produced by moving an optical projection system past the window so as to project the image of successive portions of the document onto the copy material, then it becomes necessary to move the illumination system past the window along with the optical projection system so as to illuminate those portions of the document being projected onto the copy paper. However, with the downwardly extending wall adjacent the edge of the window, the space available for the illumination system movable with the optical projection system is strictly limited. This prob.- lem becomes more acute when it is desirable to minimize the electrical power necessary to provide the proper illumination of the document by placing the illumination system closely adjacent to the window supporting the document.

Furthermore, the illumination system should have a constant light radiating characteristic so as to illuminate the document in a symmetrical manner so that all like colored portions of the document will be projected onto the image with the same light intensity. If the illumination system is composed of more than one lamp, then the light radiating characteristics of one lamp may be'different from the light radiatingcharacteristics of the other lamp, and consequently the image of the document being projected on the paper may not be uniform for all portions of the document having same uniform shade of color.

Accordingly, an object of the present invention is to lumination system for movement past the window along with the optical projection system wherein the portion of the document being scanned by the optical projection system is illuminated by a single light source.

A further object of the present invention is to provide an illumination system including an elongated light source having non-light radiatingend portions and a reflector system for concentrating the light from the light source onto the portion of the window being scanned by the optical projection system, wherein the non-light radiating portions of the light source are covered by reflectors reflecting light from light radiating portions of the light source onto the portion of the window being scanned.

An additional object of the present invention is to provide an illumination system for illuminating an elongated strip portion of an object plane wherein the illumination system includes an elongated light source and a reflector system which are both substantially coextensive with the illuminated elongated strip portion of the object plane.

Still other objects, features and advantages of the present invention will be apparent to those skilled in the art from a reading of the following detailed description of a preferred embodiment of the invention, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a partial perspective view of a preferred embodiment of a photocopying machine constructed in accordance with the present invention;

FIG. 2 is a longitudinal cross-sectional view of a portion of the machine shown in FIG. 1, and illustrating the projection of an illuminated portion of the object onto a copy paper;

FIG. 3 is a sectional view taken along the line 33 in FIG. 2, and illustrating the downwardly extending wall adjacent the edge of the window for enabling a page of a book to be copied;

FIG. 4 is a plan view of the illumination system according to the present invention;

FIG. 5 is a cross-sectional view of the illumination system shown in FIG. 4, and taken along the line 55 in FIG. 4;

FIG. 6 is a view of an in-line lamp used in the illumination system according to the present invention, and showing the distribution of the illumination intensity produced by the lamp; and

FIG. 7 is a sectional view taken along the lines 7-7 in FIG. 2.

Referring generally to the figures in the drawings, there is shown a photocopying machine, generally indicated 11, for copying an original document 13 onto a copy material 15 with a photoconductive surface. The photocopying machine 11 includes a housing 17 having a projection compartment, generally indicated 19, with a window 21 at the top of the machine 11 for supporting the document to be copied. The projection compartment 19 contains an illumination system, generally indicated 23, for illuminating the document 13 and an optical projection system, generally indicated 25, for projecting the image of the illuminated document 13 onto the copy material 15 at an exposure station, generally indicated 27. The copy material 15 has a uniform electrostatic charge and is transported to the exposure station 27 by suitable transport means, as shown in the form of an endless belt which is driven by suitable means, not shown. At the exposure station 27, the exposure of the photoconductive surface to the projected image causes a uniform electrostatic charge to be selectively dissipated to form a latent electrostatic image of the document 13. Subsequently, the copy material 15 is advanced into the nip of a roller 31 cooperating with the endless belt 29 which removes the copy material 15 from the projection compartment 19 for further processing in the machine 11. The means for driving the endless belt 29 and the cooperating roller 31 have been omitted from the description since they form no part of the present invention.

Inside the housing 17, the illumination system 23 and the optical projection system 25 are mounted in a boxlike enclosure 33 which serves as a carriage and is supported beneath the window 21 between front and back side walls 35, 37 respectively. The side walls 35, 37 extend upwardly and support the upper portion of the housing 17 so as to form the projection compartment 19. As more particularly shown in FIGS. 2 and 3, the upper portion of the housing 17 has an opening 39 formed therein with a lateral abutment 41 for supporting the glass window 21 with the upper surface thereof serving as an object plane in focus with the optical projection system 25.

To reduce the cost of the lens used in the optical projection system 25, the width of the window 21 is reduced to a minimum suitable size, for example, 8% inches, and the copying machine 11 is provided with an optical projection system 25 which is movable past the window 21 so as to scan the document 13 and project successive portions thereof onto the copy material 15.

By using a narrow window 21 with a minimum suitable width and by providing the photocopying machine 11 with a scanning optical system, the field of view of the lens may be reduced to encompass only a portion of the document 13, and hence a less expensive lens system may be utilized. As shown, to enable the optical projection system 25 to move past the window 21, the enclosure 33 serves as a carriage and is supported for easy sliding movement past the window 21 by parallel shafts 43, 45 which are secured to the front and back side walls 35, 37 respectively. The shaft 45 is received through a bushing 47 in a bracket 49 attached to the adjacent side of the carriage 33 while the opposite side of the carriage has a block 51 attached thereto which rests on the other shaft 43 secured to the'front side wall 35.

To provide easy sliding movement of the carriage 33 past the window 21, the block 51 and the bushing 47 engaging the' shafts 43, 45 respectively, are constructed from suitable materials having a relatively low coefficient of friction. For example, the bushing 47 may be constructed from a suitable bearing material, for example, an oil impregnated porous bronze composition, and the block 51 may be constructed from a suitable material, for example, nylon.

When a copy of a document 13 is to be made, the face of the document 13 is placed against the window 21 for projection onto a photoconductive surface of suitable copy material 15 located at an exposure station 27. As more particularly shown in FIG. 3, to align the document 13 with the exposure station 27, the upper portion of the housing 17 is provided with a ridge 53 extending above the surface of the object window 21 so as to provide an edge against which the document 13 may be registered. With the document 13 properly positioned on the window 21, both the document 13 and the window 21 may then be covered by a lid 55 which is connected to the housing 17 of the photocopying machine by suitable means, for example, a hinge 56 and a switch, generally indicated 57 may be actuated to initiate the operation of the machine 11.

Upon initiation of the operation of the machine 11, the illumination system 23 is energized and copy paper 15, having a uniform electrostatic charge imparted thereto, is transported by the endless belt 29 to the exposure station 27. When the copy paper 15 reaches the exposure station 27, a suitable drive for the carriage 33, not shown, is energized for moving the carriage 33 from a starting position, generally indicated 33' past the window 21 to a stopping position, generally indicated 33". The means for moving the carriage past the window 21 are not shown, since they form no part of the present invention.

As the carriage 33 moves past the window 21, the illumination system 23 illuminates an elongated strip portion of the window 21 including the portion upon which the document 13 is placed. The illuminated strip portion of the document 13 is then projected onto the photoconductive surface of the copy paper 15 by the optical projection system 25. As more particularly shown in FIG. 2, the optical projection system 25 includes an objective lens system 59 having an optical axis parallel with the window 21 and the exposure station 27 and located equidistant therebetween. The boxlike enclosure of the carriage 33 has an opening 61 in the top wall 63 through which light from the illuminated strip portion of the document 13 passes into the enclosure 33. The light from the illuminated portion of the document 13 is reflected through the lens system 59 in one direction by an upwardly facing oblique mirror 65 which is suitably mounted in the enclosure 33. On the opposite side of the lens system 59 is a planar mirror, not shown, which reflects the light back through the lens system 59 in another direction to a downwardly facing oblique mirror 67 which is suitably mounted in the enclosure 33. The mirror 67 reflects the light from the lens system 59 through an aperture 69 formed in the bottom wall 71 of the enclosure 33 and onto the photoconductive surface of the copy paper 15.

When the image of the illuminated document 13 is projected onto the photoconductive surface of the copy paper 15, the uniform electrostatic charge is dissipated in proportion to the intensity of the image. The portions of the image corresponding to the lighter areas of the document 13 have a greater light intensity and hence are more effective in dissipating the electrostatic charge on the copy paper 15 than the portions of the image corresponding to the darker portions of the document 13. The carriage 33 moves past the window 21 at uniform speed, and as an elongated strip portion of the copy paper 15 is exposed to the projected image of a corresponding illuminated strip portion of the document 13, the electrostatic charge is dissipated sufiiciently by the portions of the image corresponding to the lighter portions of the original document 13 to form a latent electrostatic image of the document 13 on the surface of the copy paper 15.

To vary the exposure of the copy paper 15 to the projected image of the illuminated document 13, the carriage 33 is provided with a shutter 70 adjacent the aperture 69 in the bottom wall 71 of the carriage 33. The shutter 70 is pivotally secured to the carriage 33 and may be moved into the path of the light passing through the aperture 69 to reduce the amount of illumination being projected onto the photoconductive surface of the copy paper 15. Since the portions of the image corresponding to the marginal portions of the elongated illuminated strip portion of the document 13 have a greater light intensity than the central portion thereof, the end of the shutter 70 has a configuration to compensate for the uneven light intensity of the image being projected onto the copy paper 15.

Stray light is prevented from distorting the electrostatic image formed on the copy paper 15 by providing suitable light shielding means, for example, bellows 72, 74, which are attached to the front and back sides 34, 36 respectively of the carriage to cover the copy paper 15 and block any stray light in the projection compartment 19 from striking the photoconductive surface. In addition, a mask 75 is provided adjacent the aperture 69 in the bottom wall 71 of the carriage 33 to prevent stray light inside the enclosure 33 from passing through the aperture 69 and striking the photoconductive surface of the copy paper 15.

To reduce the electrical power requirements needed to operate the machine 11, it is desirable that the illumination system 23 be placed as close to the window as possible to minimize the illumination that must be produced by the light source associated with the illumination system 23 to provide the required uneven illumination of the document 13 for the copying process. The spacing between'the illumination system 23 and the object window 21 is limited only by the possible scorching of the document 13 due to the heat produced by the illumination system 23 as well as the necessary mechanical clearance for locating the moving carriage 33 adjacent the upper portion of the housing 17. Furthermore, it is desirable that the illumination system 23 include a reflector system which concentrates the amount of light directed onto the portion of the document 13 being copied so as to further reduce the amount of illumination that must be produced by the lamps used in the illumination system 23.

However, to enable a page of a bound book to be copied by the machine 11, the machine 11 is provided with a wall 77 extending downwardly from adjacent an edge 79 of the window 21 so that the portion of the page placed flat against the window 21 for copying may be maximized without the binding of the book pulling the adjacent portion of the page out of focus with the optical projection system. However, with the optical projection system 25 being movable past the window 21, the illumination system 23 must likewise be movable past the window 21 and be capable of illuminating the elongated strip portion of the window 21 being scanned by the optical projection system 25, including the edge portion 79 of the window 21 adjacent the downwardly extending wall.

However, the downwardly extending wall 77 adjacent the edge 79 of the window 21 necessarily limits the space available for an illumination system movable past the window with the optical projection system. This limitation is particularly severe when it is desired to place the illumination system closely adjacent the window, because the light source associated with the illumination system necessarily has non-light radiating portions such as electrical terminals as well as electrical contacts which would normally extend a material distance beyond the edge 79 of the window 21. In the past, the uneven illumination has been accomplished by using multiple lamps in conjunction with a suitable reflector system. However, such an arrangement is undesirable because the light radiating characteristics of the two lamps are usually different, and this'results in the image of like colored portions of the original document 13 being projected onto the copy paper with different light intensities.

From the foregoing, it will be appreciated that it is desirable to have an illumination system which is capable of properly illuminating an elongated strip portion of the window 21, and yet be placed sufficiently close to the window to minimize the amount of illumination that must be produced, and hence minimize the electrical power requirements of the photocopying machine. Furthermore, it will be appreciated that it is desirable that the light sourcebe arranged in the illumination system in such a way that non-light radiating portions do not extend beyond the elongated length of the illuminated strip portion of the window, and that the illumination system includes a reflector system for concentrating the illumination of the light source onto the portion being scanned by the optical projection system 25.

A preferred embodiment of an illumination system 23 constructed in accordance with the present invention is shown in FIGS. 2-6 and is mounted inside the box-like enclosure of the carriage 33. The illumination system 23 includes a light source means, generally indicated 81,:for radiating light through the opening 61 in the top wall 63 of the enclosure 33 and a reflector assembly, generally indicated 83, for concentrating the light from the light source means 81 onto the elongated strip portion of the window 21 being scanned by the optical projection system 25.

To illuminate the portion of the window 21 being scanned in the manner diagrammatically shown in FIG. 3, the light source means 81 includes an in-line lamp 85. As more particularly shown in FIG. 6, the lamp 85 has an elongated envelope 87 terminating at its opposite ends in electrical terminals 89, 91. The envelope 87 contains a filament 93 with small light radiating portions 94, 96 spaced adjacent the electrical terminals 89, 91 respectively, which typically produce the illustrated illumination intensity distribution curve 97. Although only a portion of the curve is shown in FIG. 6, the illumination intensity distribution curve 97 is symmetriextending focal point, generally indicated 104. The.

lamp 85 is supported with the filament 93 substantially located along the longitudinally extending focal point of the elliptical reflector 99 by suitable electrical contacts 105, 107 which are located at the opposite ends of the reflector 99.

As more particularly shown in FIG. 5, the electrical contact 105 is clamped between a pair of insulating members 121, 123 which are pressed toward the base 103 of the reflector 99 by a threaded bolt 125 which is threaded into a threaded bore 127 formed in the base 103 of the reflector 99. The electrical contact 105 extends through a slot 129 formed in the base 103 of the reflector 99 and has a pin 131 secured thereto which projects laterally and engages the electrical terminal 89 at the end of the elongated lamp 85. The other electrical contact 107 is secured to the base 103 of the reflector 99 in the same identical manner and engages the other electrical terminal 91 at the other end of the elongated lamp 85 in the same identical manner, and accordingly similar reference numerals have been placed on identical parts.

As shown in FIG. 2, the optical projection system 25 has an optical path indicated by the phantom lines extending from the window 21 to the photoconductive surface of the copy paper 15. The illumination system 23 is located outside the optical path of the optical projection system, with one side portion 99' of the elliptical reflector 99 engaging the top wall 63 of the carriage 33 while theother side portion 99" of the reflector 99 extends to the optical path of the projection system 25. The portion 99" of the elliptical reflector 99 serves to shield the light radiating portions 94, 96 of the filament 93 of the in-line lamp 85 from the oblique mirror 65 to prevent the image of the filament from being projected onto thecopy paper 15.

To further increase the illumination at the marginal portions of the window 21, transverse reflectors 115, 117 respectively are secured to the sides of the carriage 33 at the ends of the elongated reflector 99 for reflecting light from the lamp 85 onto the marginal portions of the window 21. As more particularly shown in FIG. 5, the transverse reflectors 1 15, 1 17 obliquely intersect the longitudinally extending focal point of the elliptical reflector 99, for example, at a 45 angle, and cover the nonlight radiating portions adjacent the respective ends of the lamp 85, and also serve to reflect the light from the light radiating portions 94, 96 respectively, of the filament 93. In addition, another reflector 119 is located on the other side of the optical path adjacent the opening 61 in the top wall 63 of the carriage 33 to further increase the intensity of the illumination across the entire window 21 and particularly at the marginal portions thereof.

Although the illumination system 23 constructed in accordance with the present invention illuminates the portion of the window 21 being scanned in a manner closely approximating that shown diagrammatically in FIG. 3, slight variations from this desired illumination of the window may be compensated for by providing an additional light baffle adjacent the aperture 69 in the bottom wall 71 of the carriage 33. As more particularly shown in FIGS. 2 and 7, the mask has a portion bent laterally toward the optical path of the optical projection system 25, and the end of the mask 75 may serve as a light baffle and have a configuration, as more particularly shown in FIG. 7, to compensate for any deviations in the desired illumination of the window 21.

While only a limited number of embodiments have been illustrated and described, it will be apparent to those skilled in the art the various modifications and improvements may be made without departing from the scope and spirit of the invention. Accordingly, it is to be understood that the invention is not to be limited by the illustrative embodiment, but only by the scopeof the appended claims. What is claimed is: 1. In a photocopy machine having a window for supporting a document to be copied, an exposure station spaced from said window and. an optical projection system between said window and said exposure station for projecting the image of said document to said exposure station, an illumination system for illuminating successive elongated strip portions of said window comprising:

a stationary wall bordering said window on one edge thereof transverse to and substantially at the ends of said elongated strip portions, said wall having a downwardly extending surface constituting an external surface of said photocopy machine; first movable elongated light reflector means having a longitudinally extending reflecting surface with a cross sectional configuration in the form of a conic section having a vertex and at least one focal point and having a length substantially coextensive with the length of said elongated strip portions for reflecting light from a light source means onto said elongated strip portions thereby illuminating said document; light source means having an elongated configuration located at said longitudinally extending focal point of said elongated reflector and movable with said elongated reflector, including a non light radiating portion at one end of said elongated configuration and a light radiating portion adjacent said non light radiating portion;

gated reflector having a substantially planar light reflecting surface for reflecting light from said light source means onto said elongated strip portions for said first light reflector means and coacting with said first light reflector means to reflect light from said light source on successive elongated strip portions of said window;

increasing the intensity of illumination at marginal a h i movably disposed in said copying machine portions of said elongated strip portions above the and having upper and lower apertures; $222? g g 222 332225 23; figgt gx g ig said first movable elongated light reflector means, said 1i t source means and said transverse reflectcated transversely to a plane extending through the ing g disposed in said housing to project light vertex and the focal point of said elongated light reflector means, said transverse reflector disposed h g Sald aperture of i housing for obliquely to Said e1 on gal ed 1i ght reflector means m nating successive elongated strip portions of said covering said non light radiating portion at an end b f and d h l of said elongated configuration extending to intera meals assoclate Sal 5" aprture m sect said longitudinally extending focal point of Sam to regulate hght reachmg Sald expo said elongated light reflector means to cover a por- Sure statlon' 3 tion of elongated configuration of said light source a P py machllle as defined Flalm 1 m ans a d xt di b i ll to h i l wherein said second movable light reflector 15 disposed plane of said stationar wall; within said housing to coact with saidfirst light reflectand further comprising: ing means. second movable light reflector means spaced from 

1. In a photocopy machine having a window for supporting a document to be copied, an exposure station spaced from said window and an optical projection system between said window and said exposure station for projecting the image of said document to said exposure station, an illumination system for illuminating successive elongated strip portions of said window comprising: a stationary wall bordering said window on one edge thereof transverse to and substantially at the ends of said elongated strip portions, said wall having a downwardly extending surface constituting an external surface of said photocopy machine; first movable elongated light reflector means having a longitudinally extending reflecting surface with a cross sectional configuration in the form of a conic section having a vertex and at least one focal point and having a length substantially coextensive with the length of said elongated strip portions for reflecting light from a light source means onto said elongated strip portions thereby illuminating said document; light source means having an elongated configuration located at said longitudinally extending focal point of said elongated reflector and movable with said elongated reflector, including a non light radiating portion at one end of said elongated configuration and a light radiating portion adjacent said non light radiating portion; transverse reflector means movable with said elongated reflector having a substantially planar light reflecting surface for reflecting light from said light source means onto said elongated strip portions for increasing the intensity of illumination at marginal portions of said elongated strip portions above the intensity of illumination of the central portions thereof, said transverse reflector means being located transversely to a plane extending through the vertex and the focal point of said elongated light reflector means, said transverse reflector disposed obliquely to said elongated light reflector means covering said non light radiating portion at an end of said elongated configuration extending to intersect said longitudinally extending focal point of said elongated light reflector means to cover a portion of elongated configuration of said light source means and extending substantially to the vertical plane of said stationary wall; and further comprising: second movable light reflector means spaced from said first light reflector means and coacting with said first light reflector means to reflect light from said light source on successive elongated strip portions of said window; a housing movably disposed in said copying machine and having upper and lower apertures; said first movable elongated light reflector means, said light source means and said transverse reflecting means disposed in said housing to project light through said upper aperture of said housing for illuminating successive elongated strip portions of said window; and baffle means associated with said lower aperture in said housing to regulate light reaching said exposure station.
 2. In a photocopying machine as defined in claim 1 wherein said second movable light reflector is disposed within said housing to coact with said first light reflecting means. 